1. Field of the Invention
The present invention relates generally to wireless network security technology, and more particularly, to defense against a replay attack using a Prime Sequence Code Matrix (PSCM) without changing a Media Access Control (MAC) protocol in wireless network environment.
2. Description of the Related Art
In wireless network communication, it is always possible for an unauthorized third party to intrude into, or overhear, communication, destruct a communication message, or steal desired materials. In particular, a malicious intruder may find a message transmission through an arbitrary means even when a client encrypts an operation message and transmits the encrypted message to a server computer in a communication process through an arbitrary communication medium between the client and the server. Since the malicious intruder is not actually interested in message content, the message encryption is not important to him/her. However, when the malicious intruder steals or archives the message and then transmits the message to the server, the server may misidentify that the message is transmitted from the client managed by the server. If so, the malicious intruder may badly influence the server and communication by freely intruding into the server and deleting or distributing information. This is conventionally called a replay attack.
Various technologies for preventing the replay attack are being developed. For example, U.S. Pat. No. 6,633,980 discloses a method using a secret algorithm exchanged between a client and a server. The secret algorithm changes a message or a digest attached to the message by periodically modifying a predetermined replay key according to time. Even when an operation message stolen by a malicious intruder is replayed in the server, the server may defend against a replay attack by determining whether the message is received from an authenticated client since the stolen message does not match a replay key recognized by the server.
In another method a frame counter is presented. However, this method is not suitable for a standard since forgery is possible. To address this problem, a time stamp is added and used. However, since this method requires an additional header field of at least 4 bytes, there is a problem in that system load may increase and application may be possible in only a beacon message.